This invention relates to abrasive tools. More particularly, this invention relates to a method for reconditioning diamond abrasive generator wheels which are used for grinding ophthalmic lenses to a desired curvature.
Generator wheels are used in the ophthalmic industry to grind the desired curvature in ophthalmic lenses which are then fined and polished. Conventionally, generator wheels are somewhat cup-shaped with a single layer of diamond particles brazed or otherwise attached to the rim or radius of the cup to provide a grinding surface. During use, the diamond particles become worn and eventually the generator wheel must be replaced. Although the diamond and braze can be stripped and replaced with new diamond particles and braze, usually the wheel is discarded and replaced with a new diamond ophthalmic generator wheel.
In accordance with the method of the present invention, however, it has been found that worn diamond ophthalmic generator wheels can be reconditioned. Thus, it has been found that a worn abrasive tool, and in particular, a worn diamond generator wheel, having a plurality of abrasive particles bonded to a substrate by a meltable binder can be reconditioned by heating the meltable binder to a temperature at which it is liquid, reorienting the worn abrasive particles to increase their abrading effectiveness and allowing the braze to cool to bond the particles to the substrate. Preferably, additional braze paste and diamond particles are added to the substrate before heating and the new braze flows and combines with the old braze during the heating step. Also preferably, a magnetic field is employed to reorient the diamond particles.